linux-kernel - Re: [RFC] API for system clocks (oscillators)

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Message-ID: <9e4733910810300940w22786f2ate63cc828c1e66f9d@mail.gmail.com>
Date:	Thu, 30 Oct 2008 12:40:44 -0400
From:	"Jon Smirl" <jonsmirl@...il.com>
To:	"Jonas Bonn" <jonas.bonn@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [RFC] API for system clocks (oscillators)

On Thu, Oct 30, 2008 at 12:39 PM, Jon Smirl <jonsmirl@...il.com> wrote:
> On Thu, Oct 30, 2008 at 12:27 PM, Jonas Bonn <jonas.bonn@...il.com> wrote:
>>>
>>> How does this compare to the framework in linux/include/linux/clk.h?
>>>
>>
>> clk.h is pretty much just an infrastructure for "storing" clock data
>> and accessors... it does not provide:
>>
>> i) Constraints on selectable frequencies of active devices
>> ii) Notifiers on frequency change, including changes due to events
>> such as reparenting
>>
>> These are the big ones that cause headaches.  When I want to switch
>> frequency, I have to check elsewhere which devices are active and
>> which frequencies they allow.  When a frequency changes, I have to
>> manually make sure that the active devices are notified properly of
>> the change.  These are the main things that my document tries to
>> consolidate into one framework.  Like I said, I'm not sure it's the
>> right approach, that's why I requested feedback...
>
> You could probably work those features into the existing clk framework.
> clk_set_rate() could compute the constrains and return an error.
> The API could be expanded with notifier support.

BTW, most user of the clk framework are on ARM.

>
> --
> Jon Smirl
> jonsmirl@...il.com
>



-- 
Jon Smirl
jonsmirl@...il.com
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